2012 Workshop Details

WORKSHOPS - SUMMER 2012

* denotes the organizer responsible for participant diversity in the workshop

May 20 – June 10 Non-Gaussianity as a Window to the Primordial UniverseOrganizers:Neal Dalal, University of Toronto Olivier Dore, JPL, NASA Dragan Huterer, University of Michigan DongHui Jeong, CaltechMarc Kamionkowski, Caltech Fabian Schmidt*, Caltech Sarah Shandera, Pennsylvania State University

Over the last 30 years cosmological inflation has emerged as the most popular scenario that explains the origin of the primordial seed fluctuations. While current measurements from the cosmic microwave background (CMB) and large-scale structure (LSS) confirm that the spectrum of primordial fluctuations is Gaussian to a remarkable one part in a thousand, that bound is still several orders of magnitude away from testing primordial non-Gaussianity at the level predicted by slow–roll inflation, and about one order of magnitude above the level expected from non-linear post–inflationary processing of the fluctuations. The contraints on deviations from Gaussianity will improve dramatically in the near future, driven both by CMB and LSS data. A detection of primordial non-Gaussianity would open a new and extremely informative window on the physics of inflation and the very early Universe.

Maximizing the potential of discovery for large new data sets, and interpreting their results, are challenging tasks that require the development of new analysis techniques as well as theoretical modeling. This will necessitate close contact between inflationary model builders, phenomenologists and observers. This workshop aims at fostering and strengthening these ties. In addition to broadly accessible overviews of all aspects of primordial non-Gaussianity, the workshop will allow a significant amount of time for informal discussions and the development of new research collaborations.

May 20 – June 10 A Window on the Formation of the Milky WayOrganizers: Pau Amaro-Seoane*, Max-Planck InstituteMatthew Benacquista, University of Texas at Brownsville Roberto Capuzzo-Dolcetta, University of Roma La Sapienza Sofia Randich, INAF Rainer Schoedel, Instituto de Astrofisica de Andalucia

Dense stellar systems such as galactic nuclei and stellar clusters are unique
laboratories to astrophysics. The high stellar densities that are found in
their centers are at least a million times higher than in the solar
neighbourhood. Therefore, the interaction among stars plays a dominant role in
the global evolution of such systems. The complexity these systems is such
that, in spite of the huge theoretical, observational and numerical effort,
there are still a large number of open key questions. The precise astrometric observations that we will be able to make in the near future in our own galaxy
of stars and their motions contain crucial information on the star formation
history, the origin, and the evolution of the Milky Way, its nucleus and the
globular clusters. In order to develop a single narrative of the formation of
galaxies such as the Milky Way and to understand the intricate dynamics of
dense clusters, it is important for theorists, observers, and people working on
astrophysical simulations to work together to develop strategies to piece
together this picture.

May 27 – June 17 Physics of Behavior Organizers:Ila Fiete, University of Texas, Austin Ilya Nemenman, Emory University Leslie Osborne , University of Chicago William Ryu*, University of Toronto Greg Stephens, Princeton University

The idea of the workshop stems from the understanding that the role of physics in
biology is broad, as physical constraints define the strategies and the biological machinery that living systems use to shape their behavior in the dynamic, noisy, and resource-limited
physical world. To date, such holistic, physics-driven picture of behavior has been achieved, arguably, only for bacterial chemotaxis. Can a similar understanding emerge for other,
more complex living systems? To begin answering this, the workshop will bring together a diverse group of scientists, from field biologists to theoretical physicists, broadly
interested in animal behavior. We would like to broaden the horizons of physicists by inviting experts who quantify behavior of a wide range of model organisms, from
molecular circuits to mammals. We would like to
explore behavior as possibly optimal responses given the physical and the statistical structure of environment. Our topics will include, in particular, navigation and foraging, a
ctive sensing, locomotion and rhythmic behavior, and learning, memory, and adaptive behaviors.

June 10 – July 1 The Physics of Feedback Processes and their Role in Galaxy EvolutionOrganizers:Giuseppina Fabbiano*, Harvard University Philip Hopkins, University of California, Berkeley Vassiliki Kalogera, Northwestern UniversityChris Reynolds , University of Maryland

Feedback processes in galaxies are widely believed to have an important role in galaxy evolution.
Feedback from nuclear super–massive black holes (SMBHs) has been advocated as a major ingredient in reconciling cosmological simulations to the observed properties of galaxies at
different redshift, by dampening/quenching active star formation. Feedback from supernovae is clearly important in the heating and chemical enrichment of the ISM, producing the
X–ray signatures detected with Chandra in mergers, starburst galaxies, and elliptical galaxies. Most recently, it has been discussed that even feedback from active X–ray emitting
binaries may have an effect on the evolution of galaxies.

While the average energy input of these processes can be estimated, the detailed physical processes responsible for the transfer of energy to the host
galaxies and their components have not been satisfactorily addressed. Energetically, SMBH accretion can easily supply sufficient energy to unbind the ISM of a galaxy, and
so stop star formation. Whether AGNs actually do quench star formation however is unclear. Similarly, current merging simulations do not easily reproduce the observational
evidence for X–ray hot, structured and metal enriched halos in mergers. Most simulations use feedback as an input parameter, but have not tried to model the physics of this
process. Recently, thanks to high–resolution observations, from radio to X–rays, the physics of feedback has begun to receive more attention, and the current situation is
rapidly evolving with exciting prospects for progress and improved understanding.

This summer Aspen workshop will be confronting the issues involved and addressing futures approaches, both theoretical and observational, that will
produce a better understanding of the detailed physical processes responsible for shaping the evolution of galaxies. Topics will include:

Stochastic processes can be used to model systems in which two or more spatio-temporal scales interact. Turbulent flows, weather, and climate are
prime examples. Typically, the small/fast scale is treated as a random influence on the large/slow scale. The workshop will focus on improved understanding of
geophysical and astrophysical flows made possible by stochastic modeling. In particular, advances in computing power and
algorithms permit a direct comparison of stochastic models to numerical simulations. The power and limitations of the stochastic approach need to be better
established, however. The tension between simple and complex models will be explored within the context of how stochastic approaches can address the
enormous range of spatial and process scales inherent in flow and climate systems. The workshop will bring together climate scientists, astrophysicists,
applied mathematicians, and physicists to stimulate interdisciplinary research in these directions.

Long-duration gamma-ray bursts (LGRBs), associated with the core-collapse
deaths of unusual massive stars, are the fleeting signatures of extraordinarily high-energy events occurring throughout our universe. These phenomena
hold enormous promise as cosmological tools, but the full potential of LGRBs cannot be realized without first gaining a thorough understanding of their
massive stellar progenitors. Recent advances in the massive star community on binarity, mass loss, and the effects of metallicity are all critical to current
debates surrounding the nature of LGRB progenitors. Simultaneously, new results in the LGRB community have yielded important insights into the physical
properties, environmental
dependences, and interior structures of the most extreme massive stars. However, the study of massive stellar evolution and the study of LGRBs have
long been seen as separate pursuits within astronomy, with only limited communication between the two subfields. This multi-disciplinary
workshop will bring together leaders in these complementary disciplines, offering an opportunity for participants to exchange expertise, share recent results,
and consider the most pressing current questions that will shape the future of LGRB and massive star research for years to come.

July 1 - July 22 Exact Results in Gauge Theory and their ApplicationsOrganizers:Christopher Herzog, Princeton University Daniel Jafferis*, Harvard University Anton Kapustin, CaltechIgor Klebanov, Princeton University

New methods and exact results have introduced a rich new playground for formal development in our understanding of gauge theories, especially those with supersymmetry. This workshop will emphasize localization techniques, supersymmetric indices, non-perturbative dualities, relations between field theories in different dimensions, measures of the number of degrees of freedom, and related topics. The aim of the workshop is to build on the recent formal progress, explore its consequences, and look for its connections and applications to specific physical models.

To give a sense of the breadth and inter-related nature of these developments, recall that localization reduces the Euclidean path integral of supersymmetric gauge theories to a matrix model integral over a finite number of degrees of freedom. Localized path integrals of three dimensional gauge theories on a three sphere exhibit interesting symmetries that have been used to support long-standing non-perturbative duality conjectures and to find new such dualities. These matrix models have also been used to confirm certain detailed predictions of the Anti-de Sitter/Conformal Field Theory correspondence. It has been argued in certain supersymmetric field theories that the scaling dimensions of composite
operators are determined by maximizing the free energy F on the 3-sphere. Like the Weyl anomaly coefficients in even-dimensional conformal field theories, F may provide a measure of the number of degrees of freedom in three dimensions. These measures are also connected with properties of the quantum entanglement entropy. A recent proof of the a-theorem in 4-d field theory adds further focus to research on understanding measures of degrees of freedom and their evolution under renormalization group flows.

July 1 – July 29 Spin-Orbit Physics in Correlated Electron Systems Organizers: Leon Balents*, University of California, Santa Barbara Yong-Baek Kim , University of Toronto Hidenori Takagi, University of Tokyo

Recently the understanding and control of spin-orbit coupling have become subjects of intensive research across many different disciplines in condensed matter physics. In particular, spin-orbit coupling in correlated electron materials has been appreciated for its role in creating a new class of electronic states that allow crossed-responses of the electrons to electric and magnetic fields. Several new collective states of matter have been proposed in this context, including novel spin-orbital ordered states, spin liquid, various topological phases, multipolar ordered phases, skyrmion crystals etc. Equally important is the availability of increasing number of new quantum materials with significant spin-orbit coupling, including
several new 5d transition metal oxides (iridates, osmates etc), multiferroic materials, and heterostructures of transition metal systems. The spin- orbit coupling in these systems, is a critical determining factor in the nature of the electronic states and may lead to the emergence of entirely new class of quantum many-body states. The workshop aims to bring active researchers from several different, but related, disciplines and come up with coherent themes for the research of spin-orbit-induced phenomena in correlated electron systems.

July 22 – August 12 The LHC Shows the WayOrganizers:Csaba Csaki, Cornell University Andrew Liam Fitzpatrick , Boston University Konstantin Matchev*, University of Florida Tim M.P. Tait , University of California, Irvine

Particle physics is at a defining moment. The Large Hadron Collider (LHC), after decades of anticipation, is finally collecting data in earnest, running at 7 TeV collision energy. By next summer, the experiments are expected to have data samples on the order of 10,000 pb–1. Once this data is processed and analyzed, we will truly begin to explore the mechanism of electroweak symmetry–breaking. In particular, the
data will be sufficient to find evidence for or discover the Standard Model Higgs over most of the preferred mass range, and/or explore many alternative models of electroweak symmetry–breaking. This is a unique opportunity for an Aspen workshop to contribute to â€śrewriting the bookâ€ť of fundamental particles based on the results of the LHC. The purpose of this workshop is to bring together experts in diverse areas including experimentalists, phenomenologists, and model builders, in order to synthesize the results of the LHC data into a coherent picture.

July 29 – August 19 Large Fluctuations and Collective Behavior in Solids Organizers: Karin Dahmen , University of Illinois, Urbana ChampaignCraig Maloney*, Carnegie Mellon University M. Carmen Miguel, University of BarcelonaDamien Vandembroucq, ESPCI

This workshop will bring together a mix of workers from across theory, experiment, and numerical modeling, working on a broad range of systems which exhibit large fluctuations and collective behavior in their mechanical response. It will promote interactions between
participants from condensed matter / statistical physics and researchers at the boundary of physics and other disciplines such as materials science and solid mechanics. The workshop will be organized around three primary physical phenomena: 1) yielding in glassy materials, 2) dislocation dynamics and 3) fracture and fragmentation. The primary aim of the workshop will be to catalyze interactions between researchers to port common theoretical and analytical tools across the problem domains, and to connect theory with experiments.

August 12 – September 9 New Particle Physics at the LHC and Its Connection to Dark MatterOrganizers:Yang Bai , Stanford University Rouven Essig*, Stanford University Yuri Gershtein, Rutgers UniversityAndrew C. Haas, Stanford University / SLAC Jessie Shelton, Yale University Kathryn Zurek, University of Michigan

With several inverse femtobarn of LHC data allowing a detailed probe of electroweak symmetry breaking, a Standard Model Higgs will have been discovered or disproven, new physics will be discovered or increasingly constrained, and the status of the Standard Model will be under intense investigation. Simultaneously, dark matter direct and indirect detection experiments will provide an orthogonal probe of weak-scale interactions. Assembling a consistent description of the emerging picture of the weak scale is the focus of this workshop. Participation by experimentalists is highly encouraged.

Advances in genome sequencing are allowing us to understand biochemical mechanisms underlying the generation of variation in the genome. The ability to compare genome sequences from bacteria and viruses to humans is elucidating the variety of ways in which selection acts on the genome.

Organisms use a variety of mechanisms at various length and time scales to store, interpret and use information. The information itself is organized in a large and complex hierarchy: from DNA sequences to chromatin regulation to intra/extra cellular signaling to tissue/organ organization to
the interactions between organisms and species. The overall theme of the workshop is to summarize our current understanding of information hierarchies and discuss their influence on the mechanisms that allow organisms to interact, adapt, survive, reproduce and evolve. The workshop will bring together theorists and experimentalists who work on biological systems functioning at various length and time scales (cells, viruses, bacteria, eukaryotes etc.), to provide a forum in which they can share information about their expertise, with the aim of starting a dialogue which will begin the synthesis of evolutionary development at all length and time scales in the information hierarchy.

August 19 – September 9 Disorder, Algorithms and ComplexityOrganizers:Susan N. Coppersmith*, University of Wisconsin Jon Machta , University of Massachusetts Alan Middleton , Syracuse University Christopher Moore, University of New Mexico Lenka ZdeborovĂˇ , CNRS and CEA, France

This workshop will bring together researchers in physics, computer science, and mathematics to study complex and disordered systems. Systems in all three research areas share common features, such as complex free energy landscapes resulting from frustration, phase transitions, subtle correlations, and jamming. In physics, these systems include amorphous and ordered packings, spin glasses and random field magnets, glassy or amorphous systems with frozen-in disorder, pinned fluid interfaces, colloids, RNA folding, and dense packings of hard particles. In computer science, they include satisfiability, graph coloring, error-correcting codes, compressed sensing, and inference and learning problems. New approaches to these problems include belief propagation, high-temperature duality, permanent-determinant methods, and max-flow/min-cut algorithms. These algorithms can provide results on complex disordered systems that are inaccessible to both experiment and previous theoretical approaches. Moreover, many of these algorithms have interesting dynamics in their own right; they are based on a deep conceptual understanding of the physical system, and help advance that understanding.

* Organizer in charge of Diversity For more information about the Aspen Center for Physics, call (970) 925-2585 or email acp at aspenphys. org.